1. Field of Invention
This invention relates to waveguides. Specifically, the present invention relates to miniature broadband slotline and microstrip baluns adapted for use with integrated circuits.
2. Description of the Related Art
Baluns are employed in various demanding applications including Delta Sigma (ΔΣ) modulators, Direct Digital Synthesizers (DDSs), microwave high-power amplifiers, half-bridge circuits, and high frequency power converters, which are commonly used in wireless communications transceivers and advanced radar exciter systems. Such applications often demand small broadband baluns that may be incorporated into integrated circuits.
Compact broadband baluns are particularly important in ΔΣ DDS applications, where good performance over a wide range of frequencies is desirable, and where accompanying transceiver design limitations necessitate miniature baluns. Previous attempts to produce broadband baluns suitable for use in ΔΣ DDS applications include the use of coupled transmission lines and spiral inductors. Unfortunately, these devices are undesirably large with relatively limited bandwidth. For example, baluns employing spiral inductors require larger inductance to operate at lower frequencies, which results in larger baluns which are difficult to incorporate into integrated circuits and have undesirable low-frequency cutoffs.
Hence, a need exists in the art for a miniature broadband balun suitable for chip-level integration. There exists a further need for an efficient ΔΣ DDS incorporating a compact integrated balun.